This is a basic Joule thief circuit. It uses one AA (1.5) battery. When batteries are almost empty. Then there is actually still lot of energy. And it squeezes all energy out of it.
Joule thief candle
This is a basic Joule thief circuit. It uses one AA (1.5) battery. When batteries are almost empty. Then there is actually still lot of energy. And it squeezes all energy out of it.
Tauno Erik 
These are unique anf really beautiful. Had you thought of doing an exhibition (when that’s possible)?
This is a very good idea. I have to think about it.
Interesting idea indeed. I was wondering if the bottom plate is painted or oiled? Can you give some hints?
Bottom plate is from oak. And processed with steel wool + vinegar solution. The longer the solution stands, the stronger it is. “wood aging” is the search phrase.